Blade of centrifugal fans.



D. B, JACUBSEN.

BLADE OF CENTRIPUGL FANS.

APPLICATION FILED MM 213 1909 Patantd Nov. 2, 1909 UVB. JACGBSEN.

.BLADE 0F CENTRIU-AL FANS. APPLIOATION FILED MAY as, 1909.

SHEETS-(33237) Fans,

of 1905, wherein said blades are made of a fan is run at high UNITED sTATEs PATENT oEEioE. g

OLAF BERG JACOBSEN, OF ASTON, NEAR BIRMINGHAM, ENGLAND, ASSlIGrNOIR.l OF ONE- HALF TO THE ELECTRIC AND ORDNANCE' ACCESSORIES COMPANY LIMITED, 0F BIRMINGHAM, ENGLAND.

BLADE OF CENTRIFUGAL FANS.

939,136. 'Specification of Letters Patent. Ptentd yNOV, 2, 1909,

Application filed May 28, 1909. Serial No. 498,844. To all whom it my concern.`

Be it known that 1,011@e BERG J AoonsEN, i the transverse ridges'or corrugations sov that a Subject of the King of Great Britain, reeach of the laterally-separated air-cups or siding at Aston, near Birmingham, YEngl spoonings is divided, as it were, into two land, have invented certain new and useful parts located respectively on the opposite proveinents in the `Blades of Centrifugal. sides of the plain of which the following is a speciication.

This invention has reference to blades for centrifugal fans of what areknown as the multivane type in whichtlie runner is provided at the periphery, with a plurality of corrugations have their maximum y prominence at the edges of the lblade `and thelnce gradually shallow down or fall away an dle area. They said intact area, or the partlong and narrow blades arranged parallel to which is straight in its-longitudinal section, the axis of the fan and consists in iniprovemay either be fiat in its cross section, or of a ments vin the construction or formation of lflattened curve, or it maybegiven a rid eblades of the kind described in the speciticalike, ribbed or tion of the British Letters Patent N o. 14,080 ferentiatingfromthe generaltransverse section -of the blade so that it interrupts or breaks thecontinuity of the cross ridges vor corrugations and imparts that longitudinal compound corrugated formation; that is of a corrugated section longitudinally coinbined with a plurality of cross or transverse corrugations. This compound corrugated formation has the etl'ectof providing, along the length ofthe acting face of the b lade, a Series or plurality of spooiiings or air cupings, which are divided from one another Yaterally by the .transverse corrugations or ridges which extend uninterruptedly from Yedge to edge of the blade in its narrow dimension. But it has been vfound in practice that, as a consequence of the transverse corrugations corresponding' to the ridges between the air-cups, the longitudinal stiifness of the blades is impaired and they therefore have a tendency (particularly when used in fan-runners of large diameter) to bend or arch in their longer direction' under the stresses to which they are subjected when the velocities.v The object of the present invention is to remedy this defect and produce spooned or cupped blades which are 'y so stiifened or strengthened in their longer. direction as to enable them to effectually resist the bending or arching stresses, even such as may occur when a fan of large dimensions is being run at high velocities or on highpressure work. This object it is proposed to attain by einbodyin in the blade', anv integral stiifener orl stay, w ich is provided by forming the middle of the same, from end to end, with a part which, instead of partaking of the 'eneral compound ycorrugated formation, is left plain or'intact or straightv in its longitudinal ing or bending under centrifugal or other stresses. This formation does li'iotupsetthe air currents or affect the discharge of air through the ports between the .blades and as compound corrugated lformation above and below the plain or uncorrugated rib-like part, the advantages due to the cupped or spooned formation are in no wayy impaired.

Figure represents a centrifugal fan having a multivane runner whose blades areformed or conform of the This view shows elevastructed in accordance with one present invention. tions of the front blade and the back blade; the other parts of the fan being represented iii section. Fig. 2 isan elevation of one of the said'blades separately. Fig. 3 is an edge View of the a longitudinal section through part or stitfener 2.

the plain upon the dotted line ai Fig. Fig. 5 yis another longitudinal section transverse direction ofthe blade upon the dotted lilies w2- and ai respectively. Fig. 8 shows an elevation of a double curved or reflected blade iii which the series of cross by an uncorrugated longitudinal part. Fig. 9 is an edge view of the blade shown in Fig. S. Fig. l0 is alongitudinal section along the section and bisects or intersects the whole of intact or` uncorrugated area, while the transverse ridges or cross depth or merge into the said uncorrugated inidsimilar transverse section difstiffness whichresistsand counteracts archthe blades are still'cupped by virtue of their 80 `of Vthe accompanying drawings or concave 'side of one 9,0

or convex side of another said blade, and Fig. 4 is 9a taken on the dotted line w1 Fig. 2. Figs. 6 i

and 7 showtwo sections taken through the ido ridges and air cups or spoonings are bisectedj plurality of line'a- Fig. Fig. 11 is a longitudinal section upon the line @J5- m5, Fig. 8, and Figs.

12 and 13 are two transverse sections taken respectivelyupon the lines-angriff and 5 w-xQ/Figf. .-.f/The saine letters of reference indicate cor.-

responding partsin the said Figs. 1 to 7.

a is the casing of the fan and a1 its intake eye, and b is the runner which comprises a blades or vanes c, arranged in the ordinary manner between the vdisk d and the mouth-ring e at the intake side. Each of the said blades is constructed or formed, as shownin Figs. 2 to 7,with the plain lon- 15 gitudinal part 01 which runs from end to end along the middle of the said. blade, and bisects, at a right angle, thecross corrugations or transverse ridges c2 between the air cups or spoonings c3. As'shown in Fig. l,

the said plain or intact part is straight in section in the longer direction, while in its transverse section it is slightly curved7 the curvature being, as seen in Figs. 6 and 7, much flatter than the general `transverse curvature of the compound corrugated blade 3o they proceed from the edges aiattened curve, differentiating from the general transverse curvature of the blade, the said part may be quite flat, or ot any other section that will interrupt the ridges and constitute an integral or embodied stay A which imparts the desired strength and longitudinal and transverse stfitl'ness to the blades.

When a plurality of the improved bladesv ai'e builtJ into a fan-innner, their enhanced O stiffness so strengthens the structure as to tion of the latter render unnecessary the use of the tangential stay-arms or tie-rods which have ordinarily to be arranged between the hub and the mouth ring in order to prevent the distorby the centrifugal forces set up when such fans are driven at a high speed. In the fan shown in Fig. 1, no such separate stay-arms or tie-rods are used, as the blades themselves euibody their own stays and :are sullcientlyslili to keep the runner mouth ring c concentric with the eye- ,a1 of the casing, even whenl the runner is being driven at maximum speed.

.'lhe blades above described are (disregarding the uncorrugated longitudinal part) 4 i `edge o leading,

generally' of a single curved formation in the transverse or radial direction, but the improvement is also Vapplicable to'blades which have a. double-curved reflected or ogee curved transverse or radial formation, as shown in Fi s. 8 to 13, inclusive. In these figures the b ade is shown as being double curved or reflected, and the series of cross ridges c2 and air cups or spoonings 03 as' bisected by the plain or uncorrugated longhitudinal p art or stiiening area c1, which 1s disposed at the junction of the two opposite curves ofthe t 'ai'isversesection -Y As shown in Figs. 8 to 13, inclusive, the longitudinal part al, by reason of its differentiated transverse section, interrupts the continuity of the double curvature of both the ridges and the pockets c and thereby stitfens the blade or enables it to effectively resist arching and other stresses.

Preferably these blades, when built up into a runner, are arranged with the inner or presented in the direc tion, of rotation. This particular form ofY blade admits of the constructionfef large diameter fans whichl are absolutely stiff or rigid and can be driven at'much higher velocities than are obtainable, with the saine power, in fans of the same dimensions but having ordinary plain or corrugated blades.

Having fully described my invention, what l desire to claim and secure by Letters Patent is l.. A compound-corrugated centrifugal fan stay or rib blade embodying an integral substantially formation or stiii'ening area, as described. v

2. A compound-corrugated blade for centrifugal fans, embodying an integral stayor stiener consisting of a pai't or arearwhich is plain oi' intact or longitudinal section and intersects or interrupts the transverse ridges or cross corruga-v tions and extends from end to end of the, blade, substantially as described.

3. An improved compound corrugated anblade having a plain -or intactlongitudinal stitfening area for the purpose-set forth.

Ll. 'lhe improved compound corrugated fan blade having a double curved or rellected transverse section and a plain or intactlongitudinal stitl'ening area, for the pui'` poses herein referred to. 1 f

In testimony whereof I have hereunto set my hand in presence of two subscribingwit.`

ness-es.

OLAF BERG JACOBSEN. Witnesses z llenar Siinimn'i'r, HEN RY NORTON Sxgmim'r'r.

which is straight inY 

